The present invention relates to a novel organosilane compound not known in the prior art nor described in any literatures. More particularly, the invention relates to an organosilane compound in the form of a vinyl ester having polymerizability in homopolymerization and in copolymerization with one or more of other monomers and useful for the purpose of modification of various kinds of general-purpose synthetic resins or a material of gaspermeable membranes for oxygen enrichment. Further particularly, the invention relates to a vinyl .omega.-triorganosilyl n-undecanoate.